When Navy veteran Carol Roberts first met A.J. Dicken, who boasted about being the most decorated Navy SEAL ever, she was in awe of him, and she wasn't the first.

"He's a big guy," Roberts said. "He commands authority."

For years, Dicken, 57, claimed he was an ex-Navy SEAL who had served in dozens of covert combat missions, from the jungles of Vietnam to the caves of Afghanistan. He proudly wore the SEAL trident insignia and loved to show off his numerous awards. He would regale listeners about his mission to assassinate Colombian drug lord Pablo Escobar and his death defying swoop into Pakistan to make the kill shot on Osama Bin Laden. He also carried discharge papers that included two Medals of Honor, and even a laudatory email from Col. Oliver North.

But it was all an elaborate lie, one that he would allegedly use to take hundreds of thousands of dollars from his victims -- and something else harder to put a price on: their honor.

Roberts met Dicken at a military-style self-defense training school he started in an airplane hanger in Carson City, Nev., where she took some shooting and self-defense classes, along with Drs. Greg Ginn and Brian Romaneschi, who were also from the area.

"I just asked, 'What is your background?' and he said, 'I'm ex-Navy SEAL, then I went into the CIA after I retired from the SEALs,'" Ginn said.

The business was popular with the locals, and seemed to be booming. But Dicken's dream to launch his own international security firm was expensive. He convinced Ginn and Romaneschi to invest upward of $850,000 in the new venture.

"He can be very charming, very engaging," Romaneschi said. "He presents a face that kind of draws you in."

With the doctors' financial backing and Dicken's SEAL credentials, the firm Global Resources and Logistics was born, and it wasn't long before Dicken landed a big security contract with a United Nations-affiliated organization, reputedly worth about half a billion dollars.

When Roberts found out about the venture, she quit her job and became Dicken's new marketing director. Roberts said she signed up because she had seen the contracts and thought the money was coming in.

The first bit of business for Dicken's new company was in the central African country of Burundi, where planned local construction projects were hiring security providers. Dicken led a team there to meet local business partners. Roberts was part of the team, as was chief pilot Mike Reynolds, who said things started to crumble shortly after they landed in Burundi.

"By the second day, we realized that ...none of the major players there in Burundi ... knew who we were, what we were doing there," Reynolds said. "I mean, the stuff he was coming up with is just — it was insane ... the whole situation there was dangerous."

When the power went out in their hotel – a common occurrence in parts of Africa -- Roberts said the usually steely nerved Dicken became very nervous.

"He freaked out, picked up his phone ... runs into the other room talking to the CIA to have them reposition his satellite so he can make sure that the rebels aren't coming to get him," Roberts said. "He says, 'alpha, bravo, niner, niner, six, two, the fishing is good in Catalina.'"

Then, tipped off by a friend back home, Roberts and the team watched an expose about Dicken that had been posted online by retired SEAL Senior Chief Don Shipley, who runs a SEAL-style training camp in Virginia.

"If I get one more phone call asking me to verify if A.J. Dicken was ever a Navy SEAL, I'm going to take this grenade, pull the pin and blow myself up!" said Shipley in the video.

There are only about 2,500 active Navy SEALs, among the elite of the elite in the U.S. military. Shipley and his brothers in arms say it's a slap in the face for people to pretend to be SEALs. Shipley had made it his personal mission to ferret out phonies and uses a special government database to keep track.

Shipley said Dicken was a different case from the others. For one thing, his claims, showing off medals and discharge papers were so over the top. He said he even blew up an earlier scheme where Dicken tried to con a filmmaker out of $50,000 by claiming he was the SEAL who killed Osama bin Laden.

"Oh, he says he has got two Medals of Honor, that hasn't happened since World War I ... a POW? There's no listing," Shipley said. "A.J. has a mental problem, and I go after the worst of the worst."

After the Burundi team saw Shipley's video, the last bit of Dicken's cover was blown and the expedition became a rescue mission.

"You're sitting in the middle of Africa with somebody that you're pretty convinced at this point is a sociopath at best, a psychopath at worst," Roberts said.

Back in Nevada, the two doctors, already on the hook for hundreds of thousands of dollars, wired thousands more in emergency cash to bail out Dicken and the rest of the team. After they made it home, Roberts wasted no time blowing the whistle on her boss.

"I went to one of the doctors with all of the evidence I had and said, 'You have a problem,'" she said. "It was all a great big fraud."

Dicken fled Nevada. Roberts said she believes she and others fell for his ruse because he "brought a level of plausibility."

"He wouldn't tell these outrageous stories just right off the bat," she said. "He would drop little bits of things that are plausible. And he would tailor that plausibility story to each person, knowing what they knew."

Dicken kept a low profile for months, but in February, KGO, ABC's affiliate in the San Fransico Bay area, tracked Dicken to his parents home in Southern California, where he denied ever having claimed to be a Navy SEAL -- and promptly disappeared once again.

This past fall, "20/20" tracked Dicken to a secluded property in rural Arkansas. When "20/20" finally caught up with him, he refused to comment.

Now Dicken faces felony firearms charges in Nevada, thanks to videos he had made at the training academy in Carson City that showed him firing a variety of high-powered weapons. Because Dicken is a convicted felon, he's banned from owning firearms.

Dicken's now-debunked claims of SEAL glory have the people who say he conned them hoping to see him wear a very different kind of uniform -- the orange jumpsuit kind prisoners wear.

"My payback is going to be my satisfaction," Roberts said. "I would like to see Dicken … arrested and brought to justice. ... He's a coward and a liar. That's all he has been, and that's all he ever will be."